Pneumatic pruning shears



Dec. 25, 1945` l.. BRowNxNG 2,391,676

PNEUMATIC PRUNING SHEAR I Filed April 14, 1944 Patented Dec. 25, 1945 UNITED STATES PATENT OFFICE PNEUMATIC PRUNXNG SHEARS Leander Browning, Greenwood, Ind.

Application Aprll14, 1944, Serial No. 530.975

2 Claims.

The object of my invention is to provide an automatically-reciprocating, pneumatically-actuated, single action tool.

The accompanying drawing illustrates my invention as embodied in a pruning tool.

Fig. l is a side elevation of the complete tool;

Fig. 2 is an axial section, on a larger scale, of th'e valve portion of the tool, with the parts in normal position;

Fig. 3 is a view similar to Fig. 2 with the parts in the positions immediately following forward movement of the cutting element:

Fig. 4 is an axial section, on a smaller scale, of the tripper mechanism and adjacent parts; and

' Fig. 5 is a section on line '5--5 of Fig.4.

in the drawing lll indicates a main tubular barrel supplemented by the tubular extension I' provided at its outer end with a cutter bill I I. Reciprocable within barrel Ill-I0' is a plunger rod I2 to the outer end of which is secured knife I3 adapted to coact with cutter bill il. The inner end of plunger rod I2, within barrel IIJ, is provided with a piston head I4 and packing cup I4' which flt barrel Ill, and rod I2 is biased to its innermost position by springs I5, I5 attached at one end to rod I2 and at the other end to a header or plug I6 at the junction between parts I0 and I0', as indicated by dotted lines in Fig. 1. Between piston I4 and plug I6, rod I2 is encircled by a buffer spring ll engaging abutment I8 on rod I2 and engaging plug I8 at the end of the forward stroke of rod I2 after knife I3 has coacted with bill il.

Rod I2, intermediate its length, is diametrically slotted at (Fig. 4) to receive the latch 2l pivoted at 22. Latch 2l is medially slotted at its free end to form a latch linger 23 and a stop finger 24. The Width of latch 2I exceeds the diameter of rod I2 so that it projects radially at opposite sides of rod I2 and extends into keyways 25, 26 formed in the guide ring 2l mounted within barrel I0. Pivoted at 28, in keyway 25, is the trigger 29 having an abutment shoulder 30 for reception of the tip of latch nger 23, and a nger 3| overlying said linger 23. Rod I2 within the area between ngers 23 and 24, is transversely bored to form a pocket 32 within which is seated a spring 33 engagingnger 23 and normally biasing the latch 2| to the position sh'own in Fig. 4.

Trigger 29 is biased to the position shown in Fig. 4 by spring 34 and, in order to ease operation of the trigger, I provide linger lever 35 pivoted at 36 on yoke 3l secured to barrel I0 and connected to the trigger by link 33.

' Latch 2I sliding in the keyways 25 and 28 prethe latch 2I is swung to the left to clear the latch from obstruction by the trigger.

'I'he lower end of barrel I 0 is closed by the axially bored plug 40 provided with sealing cup 4I which' provides an air tight association with barrel l0.

The specic construction of the trigger mech'- anism described above, forms the subject matter of my divisional application Serial No. 621,768, iiled October 11. 1945.

Plug 40 is provided with an inwardly extending tubular portion 42, radially perforated at 43 just inside cup 4I.

The outer end of plug 40 is provided with a threaded nipple 44 to which is secured the tubular valve casing 46 having an intermediate valve seat 41 the inlet side of which may be engaged by a valve 48 biased to seating position by spring 49 abutting ring 50 mounted within casing 46. Casing 46 is threaded at its outer end to receive a supply line 5I for compressed air.

Slidable within tube 42 is the lower end of a. tube normally urged inwardly by spring 6I. Reciprocable within tube 60 is a rod 62 longitudinally slotted at 63. A pin 64 carried by tube 42 projects through slot 63 to limit the axial play of rod 62. The lower-or outer-end of rod 82 is ensmalled at 65 to enter and seat in the axial bore 86 of actuator 6l resting at its outer end on valve 48. The parts are so proportioned that when tube 60 is in its lowermost position, actuator 61 presses valve 48 away from its seat and when tube 60 is in its uppermost position, valve 48 is seated to prevent ingress of compressed air between plug 40 and piston I4.

Tube 60 is longitudinally slotted at 68 and through this slot projects cross-arm 69 of rod 62. Tube 68 is also longitudinally slotted to register with slot 63 of rod 62 and pin 64 extends through both' slots and forms the pivotal support of a latch 'Ill perforated at 1I for reception of one end of cross-arm 69. Latch 'I0 is biased to latching position by spring 12 and is provided at its free end with a cam 13 arranged to be engaged by a cam I4 carried by tube 60.

Reciprocably mounted in the inner end of tube is the stem 15 of head I6 engageable by piston I4. Stem l5 is longitudinally slotted at 'll and its axial movement relative to tube 60 is limited by pin 18 passing through said slot.

A compression spring 80 is interposed between stem 15 and rod 62 and a compression spring 6I is interposed between head 16 and tube 60. A pin 32, carried by stem 15, projects between the coils of spring 8| so that, by turning said spring one way or the other on stem 15 more or less of the coils of spring 8| may be caused to lie between pin 8| and tube 69 thereby adjusting the force of said spring between head 16 and tube 69.

An exhaust tube 90 perforates cup 4I and communicates with exhaust passage 9|. At its inner end tube 99 is enlarged into a valve chamber 92 transversely ported at 93. The reciprocable exhaust valve 94 serves to open or close ports 93 and is provided with a stem 95 threaded into the valve, projected through a diametrical perforation in cross pin 69 and headed at 9S. A

spring 91 encircling stem 95 :between valve 94 and cross pin 96 biases valve 94 toward port closing position, and head 96 in engagement with cross pin 69.

Normal positions of the parts are shown in Figs. l, 2 and 4, inlet valve 48 beingopen, exhaust ports 93 closed, the space between cups 4| and I4 lled with compressed air and rod I2 and cutter I3 held in restricted position by latch 23 abutting trigger 29.

Pull upon nger lever 35 causes linger 3| to swing latch 2| to the left so that finger 23 will clear trigger 29, thus freeing piston I4, to yield to the compressed air behind it, whereupon the following movements take place in the order named: Head 15 moves forwardly to the extent of slot 1-1; spring 6| moves tube 60 forwardly to bring the lower end of slot 68 against cross pin 69 and then to bring cross pin 69 against head 96, at the same time retracting pin 66 from actuator 61 thus permitting spring 49 to close inlet valve 48, whereupon further movement of cross pin 69 lifts valve 94 to open exhaust ports 93. By this time, knife I3 has coacted with bill Opening of ports v93 relieves the air pressure on piston I4 and thus permits springs I5 t0 return piston I4 to initial position.

The initial forward movement of tube 60 withdraws cam 14 from cam 13 so thatlts perforation 1| may drop over crosspin 69 and thus retain exhaust valve 94 in open position until piston I4 has been returned to engagement with head 16 to iirst compress springs 8| and 80 and then move cam 14 to withdraw latch 10 from cross pin 69 whereupon spring 80 acts to withdraw cross pin 69 from head 96 and permit spring 91 to close exhaust valve 94 over ports 93.

Whenl piston I4 is fully retracted, part 65 of rod 62 engages actuator 61 to open inlet valve 48, finger 23, in the meantime. having moved in behind trigger 29 to hold rod I2 and its piston I4 and cutter I3 against a second projection until trigger'29 is again actuated.

I claim as my invention:

l. A pneumatic implement comprising a main barrel, a piston therein, means biasing said piston to retracted position, trigger means releasably holding said piston against protraction, an inlet valve normally biased to closed position, a reciprocable rod arranged to act on said inlet valve against its bias, a latch arranged to engage said rod and releasably hold it in position permitting closure of sa-id inlet valve :by its biasing means, a cam movable relative to said latch to retract said latch from said rod, means associated with said cam for engagement by said piston to control cam movement. an exhaust valve controlling an exhaust port for said barrel, and a lost-play connection between said rod and exhaust valve.

2. A pneumatic implement comprising a main barrel, a piston reciprocable therein, means biasing said piston to retracted position, manually controlled means for blocking protractive movement of the piston, an inlet valve controlling flow of pressure air to the piston in protracting direction, meansbiasing said valve to closed position, a reciprocable tube aligned with the piston ,between piston and inlet valve, a spring biasing I said tube in piston protracting direction, a reciprocable rod in said tube and contacting said valve in opening direction only, a spring in said tube biasing said valve in valve-opening direction, an exhaust valve and a connection between said exhaust valve and rod.

LEANDER BROWNING. 

